@media only screen and (min-width:640px){
    html {
        font-size: 32px;
        background: #8cbc8b;
    }
    body {
        width:640px;
        margin: 0 auto;
    }
    .top,.btn-float,.footer ul{ width: 640px;}
}
@media only screen and (min-width:620px) and (max-width:640px){html{font-size:32px}}
@media only screen and (min-width:600px) and (max-width:620px){html{font-size:31px}}
@media only screen and (min-width:580px) and (max-width:600px){html{font-size:30px}}
@media only screen and (min-width:560px) and (max-width:580px){html{font-size:29px}}
@media only screen and (min-width:540px) and (max-width:560px){html{font-size:28px}}
@media only screen and (min-width:520px) and (max-width:540px){html{font-size:27px}}
@media only screen and (min-width:500px) and (max-width:520px){html{font-size:26px}}
@media only screen and (min-width:480px) and (max-width:500px){html{font-size:25px}}
@media only screen and (min-width:460px) and (max-width:480px){html{font-size:24px}}
@media only screen and (min-width:440px) and (max-width:460px){html{font-size:23px}}
@media only screen and (min-width:430px) and (max-width:440px){html{font-size:22px}}
@media only screen and (min-width:420px) and (max-width:430px){html{font-size:21.5px}}
@media only screen and (min-width:410px) and (max-width:420px){html{font-size:21px}}
@media only screen and (min-width:400px) and (max-width:410px){html{font-size:20.5px}}
@media only screen and (min-width:380px) and (max-width:400px){html{font-size:20px}}
@media only screen and (min-width:360px) and (max-width:380px){html{font-size:19px}}
@media only screen and (min-width:340px) and (max-width:360px){html{font-size:18px}}
@media only screen and (min-width:320px) and (max-width:340px){html{font-size:17px}}
@media only screen and (min-width:300px) and (max-width:320px){html{font-size:16px}}
@media only screen and (max-width:300px){html{font-size:15px}}